A vertical-axis wind turbine (VAWT), also called a Darrieus wind turbine, is widely known. Such a wind turbine has two or more turbine blades (having a wing profile), which turbine blades are located rotation-symmetrically with respect to the vertical axis. A Darrieus wind turbine has as an advantage over a wind turbine with a horizontal axis (HAWT) that there is no need to pitch it in the direction of the wind. Another advantage is that the work generated by the VAWT can be used in a simple manner, usually using a generator that is arranged stationary. In this way the construction of the wind turbine can be lighter and cable twist is avoided, which makes the control of such a wind turbine easier than that of a HAWT. The turbine blades of the oldest type of VAWT are straight, vertically arranged turbine blades having a wing profile. Because of the “centrifugal force” which occurs during rotation, said blades are exposed to large forces. Therefore later developments have led to curved turbine blades having a catenary line or troposkien shape. Wind turbines having a vertical axis have as a disadvantage that they do not readily start up when the wind starts blowing. Therefore, it has long been known to provide these wind turbines with a Savonius rotor, which solves this problem.
In order to be competitive with others means of generating energy, in particular in order to compete with fossil fuels, there is a constant need to reduce the production cost of the wind turbines. With wind turbines however, numerous others factors play a contributory role, such as noise pollution, strength in case of extreme winds, reliability during operation and sensitivity for maintenance etc.